Symptoms

Getting an "Object reference not set to an instance of an object" error when calling the List method of a SmartObject (which was created off of a SQL table). When calling this method in the SmartObject service tester, it works fine.
 

Diagnoses

Running a view generated from the SmartObject list method generated the error. Configured the rule to return single row with inputed ID works fine for some and some error out with the same error message. Compared the row returned without error and the row returned with error for data difference (email, photo, phone number, ect...).
 

Resolution

After further research, the Profile_Photo data field was not the cause. The email_hyperlink data field was in an href format, which caused the issue. Once removed, the issue went away.